code: def lookup_all(base):
      """Looks up a subclass of a base class from the registry.
  
      Looks up a subclass of a base class with name provided from the
      registry. Returns a list of registered subclass if found, None otherwise.
  
      Args:
        base: The base class of the subclass to be found.
  
      Returns:
        A list of subclass of the name if found, None otherwise.
      """
      basename = base.__name__
      if basename not in _registries:
          return None
      registry = _registries[basename]
      output = []
      for name in registry.keys():
          init_args = registry[name][_INIT_ARGS]
          if init_args is not None:
              output.append(registry[name][_TYPE_TAG](**init_args))
          else:
              output.append(registry[name][_TYPE_TAG])
      return output
  
file_path: model_search/model_search/registry.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import inspect
  import traceback
  from absl import logging
label_desc: Use image node_id 4 for calling a global function with example usage: lookup_all(base) and returns: output, None